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  1. #1

    Default 347 dyno results

    I dropped my car off at Redline Motorsports in Illinois to get a few things done to it and I just got the results.

    Its a stock block 347 in a 85 gt with a T5.
    10;25.1 compression
    AFR 185s
    236/243 .603/.588 108 lsa cam
    non ported Victor Jr. intake
    quickfuel slayer 750 carb with 2Ē HVH super sucker carb spacer
    MSD ignition and stuff


    Im very satisfied with the shop, Iíve been communicating with them via email because Iím currently stationed in Korea. Matt always responded very quickly to all my emails. I only had them install the distributor, ignition, carb spacer, a couple other small things and I had them dyno and tune the vehicle.

    I was was hoping for at least 400, so Iím going to have to do a couple things to see if I can get to my goal.
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  2. #2
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    Very nice, almost 400 RWHP and a T-5 should be a lot of fun to drive!

  3. #3

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    Thanks. I’ve already got a 8.8 I’m going to swap in it after I install a 4.56 gear. I’m going to strip most of it out, I’m shooting for high tens with it.

  4. #4
    FEP Power Member Hemlock's Avatar
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    430 hp on the block is not too bad and right in line with what that combo should produce. I would be very happy with those numbers. Curious to see what it does at the track. What does your car weigh? Should put you in the mid to low 11's providing you can get traction.

    Robert
    1984 RS 347 Capri, To many car parts to list, check out my car build page here for the story on my car and a full parts list/setup!:

    My RS in Action

  5. #5
    FEP Super Member xctasy's Avatar
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    I use a T5 and 7.5 to 9" axle correction factor of 1.264 to get net installed figures. The dyno correction factors I use are the sterner 1972 onwards US Production car SAE net sea level and air temp corrections, which can drop things a little.

    To me, this is a 486 hp net at 6350 rpm engine with 428 lb-ft at 4800 rpm.

    Nice numbers.

    Thanks for serving. In NZ, I have had the pleasure of having many Korean friends. Click on the first link in my profile footer. Care of Hemlock above.

  6. #6

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    I’m not sure what the car weighs yet but it’s an 85 gt with cloth interior, manual windows and locks, aluminum heads, and no ac compressor. When I get back I plan on stripping most of it and going with team z tubular everything up front. I’ll be shooting for 2700 lbs or so.

  7. #7

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    Do a mild port/polish and gasket match on the heads and intake and you're there. I had a very similar 347 with a Hurricane intake and RPM performer heads I ported and was at 412 hp and 384 tq............w 3.73's in a stock 84GT I was at 11.70's

  8. #8

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    You get down to 2700 you are where you are hoping on ET if it hooks. &nbsp;I would probably model things in software to double check cam timing vs your desired RPM range. &nbsp;A little retard on cam - not more than 5 degrees - often moves the power band up and builds more peak output. That plus more timing advance and better fuel may be all you need.<br><br>Or once there's better fuel, shave the heads and jack the compression up some more... &nbsp;<br><br>I would verify you have the strongest pushrods available and are using short leakdown height modified hydraulic lifters or solids. &nbsp;Springs and retainers need to be up to the task also in order to maintain positive valve control. &nbsp;That will give you your best reliable peak -- and what I mean here is best peak with the fewest broken parts. &nbsp;Can win if you break!<br><br>The 3.40 stroke often associated with a 347 unless it's in a big bore race block. &nbsp;That much stroke can hurt you a little on ring seal and other stuff once the R's come up. &nbsp;It becomes an average feet per second game. &nbsp;Rotating assembly parts have to be up to the challenge too of course.<br><br>With near OE strength parts and good fasteners, a 3" stroke is getting out where things tend to break unless more than typical build things are done around 7000. &nbsp;Physics says a 3.25" stroke and a 3.4" stroke are shorter yet.<br><br>Personally I will only run a OE parts setup 3" stroke to 6750. &nbsp;3.25" to 6250 or 6500 if I've balanced it.<br> <br>Really hate the idea of that much with a 3.4" stroke unless it's both heavily fortified and balanced. &nbsp; Anything near OE stuff I'd limit to not more than 6000 --&nbsp;and mainly that even much because a lot of heads and intakes done see their potential get used until then or higher.<br><br>Some guys approach race motors from a cubic feet per second game perspective. &nbsp;They go after peak horsepower and the short stroke big bore with lots more R's gets them there plus the longer rods yield more quench time too. &nbsp;Just stuff to play with.<br><br>not sure if you've ever considered throwing RPM at your motor might reach your ET goals more than a full on stroker build will.<br><br>Years ago I saw a guy running a fiberglass frontend tube chassis 55 Chevy with a 283 bored 0.090 to make it a 302. &nbsp;It was crammed so radical it wouldn't "idle" at all below 2000 and was choppy until 2500. &nbsp;Compression was through the roof. &nbsp;He had dual magnito ignition and a tunnel ran with two 600 CFM 4 barrels on top. &nbsp;He left at 9500, shifted at 11500, and ran her out the big end at 12500. He was running high 8 second 1/4 miles in N/A trim with it. &nbsp;Way beyond crazy RPMs are possible with SBF motors too, but the block has to be very strong and the parts have to go way beyond OE &nbsp;too. &nbsp;<br><br>He had around 60K wrapped up in that motor and it would cost him around $15K he said every time he rebuilt it. &nbsp;But is was a bad ass bitch that drank a fuel cell worth of race gas on every pass and turned 8's NA back when 10's out of a bigblock was considered near impossible... &nbsp;he laughed his ass off at all the huge CID cars he would rip around on the big end.<br><br>I've often imagined that type of build with intercooled dual stage turbos or a supercharger fed by turbos. &nbsp;Would be fun!

  9. #9
    FEP Super Member xctasy's Avatar
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    As erratic50 said
    Quote Originally Posted by erratic50 View Post
    You get down to 2700 you are where you are hoping on ET if it hooks.

    I would probably model things in software to double check cam timing vs your desired RPM range. A little retard on cam - not more than 5 degrees - often moves the power band up and builds more peak output. That plus more timing advance and better fuel may be all you need. Or once there's better fuel, shave the heads and jack the compression up some more. I would verify you have the strongest pushrods available and are using short leak-down height modified hydraulic lifters or solids. Springs and retainers need to be up to the task also in order to maintain positive valve control. That will give you your best reliable peak -- and what I mean here is best peak with the fewest broken parts. Canít win if you break.

    The 3.40 stroke often associated with a 347 unless it's in a big bore race block.

    That much stroke can hurt you a little on ring seal and other stuff once the R's come up. It becomes an average feet per second game. Rotating assembly parts have to be up to the challenge too of course.

    With near OE strength parts and good fasteners, a 3" stroke is getting out where things tend to break unless more than typical build things are done around 7000. Physics says a 3.25" stroke and a 3.4" stroke are shorter yet.

    Personally I will only run a OE parts setup 3" stroke to 6750. 3.25" to 6250 or 6500 if I've balanced it. Really hate the idea of that much with a 3.4" stroke unless it's both heavily fortified and balanced. Anything near OE stuff I'd limit to not more than 6000 -- and mainly that even much because a lot of heads and intakes done see their potential get used until then or higher. Some guys approach race motors from a cubic feet per second game perspective. They go after peak horsepower and the short stroke big bore with lots more R's gets them there plus the longer rods yield more quench time too.

    Just stuff to play with;-

    Not sure if you've ever considered throwing RPM at your motor might reach your ET goals more than a full- on stroker build will. Years ago I saw a guy running a fiberglass frontend tube chassis 55 Chevy with a 283 bored 0.090 to make it a 302. It was crammed so radical it wouldn't "idle" at all below 2000 and was choppy until 2500. Compression was through the roof. He had dual magneto ignition and a tunnel ran with two 600 CFM 4 barrels on top.

    He left at 9500, shifted at 11500, and ran her out the big end at 12500. He was running high 8 second 1/4 miles in N/A trim with it. Way beyond crazy RPMs are possible with SBF motors too, but the block has to be very strong and the parts have to go way beyond OE too. He had around 60K wrapped up in that motor and it would cost him around $15K he said every time he rebuilt it. But is was a bad ass bitch that drank a fuel cell worth of race gas on every pass and turned 8's NA back when 10's out of a big block was considered near impossible...;he laughed his ass off at all the huge CID cars he would rip around on the big end. I've often imagined that type of build with intercooled dual stage turbos or a supercharger fed by turbos. Would be fun!

  10. #10

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    Wow - that post got corrupted! I was in poor coverage... thanks for fixing it!

  11. #11

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    Hmmms.... that would have been 0.120 over, not 0.090. Easier thing to do on the bow tie stuff is use a 283 crank in a 327 block.... not that many people build that old stuff anymore. About as rare as people building 260's and 289's in the SBF family. Possible but rare.

  12. #12

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    Was thinking about the 4.56's. You really do not want to need 5th. Generally a 9.99 needs enough MPH that if you rev to 6750 with a 3.90 on a 26" tire you just barely make it.

    4.56 - not sure if you'll make the stripe off the rev limiter in 4th shooting for high 10's. A 4.30 might be better.

    The other problem is a 3.35:1 low gear is way steep combined with a 4.56. You will be better off with a 2.95:1 low gear. T5Z might hold the power better anyway. Or a T56 built viper spec


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  13. #13

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    I plan on running a 28” slick. That should keep me in 4th, no?

  14. #14

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    According to several sites like this one http://www.autosnout.com/Quarter-Mile-Car-List.php

    You need around 125 MPH to break into the high 10's and 137 mph to break into the high 9's.

    With a 4.56 and 28" in 4th gear (1:1) you're looking at 6840.

    4.30 with a 28" is 6450.

    4.10 with 28" is 6150.

    btw - 3.90 at 6412 with a 28" tire gets you to 137 mph.

    Personally I would have reservations about spinning a 3.40" stroke past 6000 unless it is balanced and VERY stout on the bottom end with significant ring tension. Otherwise you will blow it up frequently of get stuck rebuilding it often.

    Its actually less stressful on parts spinning a 306 long rod to 7500 or even 8000 than spinning a 347 to 6250. Have to look at average FPS or FPM at the rings. Drag racing yields a big peak in speed for a short blip - how long will it hang in there between rebuilds? This is a decent predictor

    A big bore block with a 3" stroke would be pretty interesting. Especially with boost.
    Last edited by erratic50; 11-04-2017 at 12:15 AM.

  15. #15

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    Decent video on engine redlines
    https://youtu.be/Vy2r3p-SOag

  16. #16

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    It’s an internally balanced Eagle bottom end rated for 1500 horsepower, so it’s a bit of overkill there. As far as ring tension, I have no idea. I had this engine built about 6 years ago and it’s been sitting since. Everything I talked about with the builder was to shift at 6800 with a 28” tire, so I’ve been going off the plan we had originally.

  17. #17
    FEP Super Member xctasy's Avatar
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    Nice engine. I smiled when I saw what crank you were running, john85gt.


    From what I've heard, Internal balancing is an answer to some of the endemic stock 302W block splitting problems at 7000rpm.

    Ford started doing so much work on the 289 HP, 302 G code Tunnel Port and Boss 302 engines, and the 1981 50 ounce revision was really a production stop gap. It never really worked on the 5 liter production race cars, and right about then, out comes the SVO internally balanced crank for A3 headed 9.2 ad 9.5" deck 351s, and that then appreared in cut down form on the SVO 5 liter race engines. Every AVESCO Windsor/Boss alloy head and iron SVO block 5 liter has had the fully counterweighed Ford design crank

    The old internaly balanced Ford SVO cranks were ligher than those that were 28 or 50 Ounces....it was primarliy a cost and space issue that prevented Ford doing it earlier.

    Ford patterned the Windsor 5 liter off the ancient Y block 4.375" bore transfer line, and the cranks got downgraded for 1962 to meet weight and cost targets. Now, things are swinging back, because USA design and 55 years of information from that 1962 Stirrat SBF redesign of the Y block has proven a lot of things. Some of that information was from the other GM divisions, who used re-hashed Ford parts. The Y block crank in Australian Stroker Holdens built by Victor Meli from 1978-1988 or so was a very notable example.

    The first "factory" clue that the common block breakage might be Detriot out of balance crank related was when the 1985 GM Australia's Holden Division started emerging with fully internally counterweighed cast iron cranks that allowed 350 engines on 304 and 308 blocks, or that could survive 6 hours at 100 mph average lap speeds. The kiiler 3.48" stoke crank was made by outsiders well before the 1997 235i GTS engine. The funny thing is they were almost an exact 4.4" bore spacing copy of the 312 or 292 Y block truck forged steel crank design, but in nodular iron. Even funnier, every OHV Chevy Alloy LS engine has looked more and more like a 1969 351 Windsor V8 with a tall deck Ford GT40 255/305 "Indy" engine block....



    Anyway, evidence seams to be that saving an iron block by fulling internal counterweighing is a partial answer to unloading the stock block. Ford has done this on its six cylinder engines, and also the Modular 4.6/5.0/5.4's. When they beefed up the Teksid based Ford Modular block, they were then free to go to nuts on flat plane Ferrari style cranks.

    What comes around, goes around.


    Note well.

    Quote Originally Posted by erratic50 View Post
    Hmmms.... that would have been 0.120 over, not 0.090. Easier thing to do on the bow tie stuff is use a 283 crank in a 327 block.... not that many people build that old stuff anymore. About as rare as people building 260's and 289's in the SBF family. Possible but rare.




    Compartive to GM's Chevrolet divisions 1958-1986 SBC, Fords 1969-2001 302 takes about 1 pound of iron out of each thinwall cylinder compared to any early SBF Chev, or Siamese bore Dart, World or FRPP block, and the those aftermarket blocks sit at about 245 thou for cylinder wall thickness at the trust faces, before a 1/8" 4.125" overbore.

    It just so happens that the "283" was able to be over bored because of that 245 thou thinwall casting. Fords effective casting thickness was 187 thou based on the Cleveland plants 1969 six cylinder quality assurance tests which the late Ak Miller was free to discuss in 1970. Additionally, the cylinder bores in 1969 were downgraded from about a nominal 180-200 thou to between 120-140 thou in a revised "shell moulding" process, which gave the bores an eggshell section not present in the 1962 to 1968 Windsor and Cleveland made 221/260, 289 and the first joint design 289/ 302 small blocks of 1968.

    This process was discussed by Australian Brad Girdwood of "Brads Speed Shop" in the Australian Hot 302's and 351s book in the late 80's. Ford Small block engine builders suffered a lot more in the detonation prone Cleveland engines, which had the Cleveland plant thinwall techniques, and also the very rough combustion canted valve heads. The gain in having a solid 40 hp more than any Windsor engine was lost in block scrapage, and it was a pandemic issue for any engine builder who didn't have acess to a supply of factory Ford blocks to draw upon.


    In just the cylinders, shell molded thin wall small block Fords take about 8 pounds of cast iron out of the 8 cylinders in total, and about 65 pounds out of the bulkheads and flanges and walls of the block.

    Protecting a thinwall Ford Small block is about getting the ring clearances and bore honing quality right, and then about good internal components. If you are not using Cleveland heads, the block will last a lot longer than if you are. Modern alloy SB 302 heads are the best thing sinced sliced bread.

    Ford's Model T cost cut and build down to a price philosophy is a sound one if you know the rules. I've posted this before elseware http://vb.foureyedpride.com/showthre...21#post1860221

  18. #18
    FEP Super Member xctasy's Avatar
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    The Patrick Hale Trap Speed formula (Peak Flywheel HP = (Trap Speed/234)^3 * race weight.

    A formula that is his cannot be copywrited.

    http://www.stealth316.com/2-calc-hp-et-mph.htm

    Due to a lack of proper statistical methods, drive train loss against SAE net or DIN net flywheel hasn't been declared or reported in this, but as a manual transmission or optimised trans braked automatic car, its bang on.

    I used a 1.264 factor, because Cam Benty researched this in Car Craft in 1983, and the 4-bbl 1983 Ford and Z28 5.0 5 speed were assessed.


    I use Jeff Lucius information not because its the best, it isn't, it has major issues which I discussed with him about 8 years ago, but he has each foundational part listed. Vizard's formula is supperior, and it covers all aspects better, but Mr Lucius revels his sources. Vizard reveals the answers, and like Vizard, he doesn't go into why unless you Really Wanna Know it All.



    486 hp = 132.15 mph/234^3 * 2700

    David Vizard used the variations of the Hale and Fox RWHP calculations that Moroso uses, except he plugged in frontal area, body drag factor , and cubic inches verses startline mass in his 1987 2nd edition of the A Series book. Right then and there, the true baseline of rear wheel hp to ET and MPH was defined, and although it was Cam Benty who was the first to resolve rwhp to flywheel hp, since 1987, everyone has spent most of the time arguing about HP Losses from the engine to the drive train.

    Gearing is best set to over speed 10 to 15% past the 6350 rpm power peak to ensure every last hp is used, but a stock 5.0 block won't like 7000 rpm, so your forced to compromise on the Idealised Dream Wheel gearing, and aim for 6667 rpm up shifts with 5% over power peak changes.

    4.20:1 gears would be ideal at 6667 rpm
    4.00:1 gears would be ideal at 6350 rpm

    With 28" tires and 4.2's, I get 10.32 second 1/4 miles at 132.15 to satisfy 486 flywheel hp.


    Of course, as Dick Johnson said in 1984 when stuck with the wrong ratios with his 5 speed 5.0 Mustang...."nobody says you have to use all 5 gears..."

    That means you can use, say, a crazy wide ratio 4cyl T5 gear set, effectivey allowing you to use something like a set of 3.08:1 gears, and just run the T5 Turbo wide ratio gear set.




    A 4.00 to 4.20 axle with 28" tires and 2.95/1.94/1.34/1.00/0.72 to 0.63 hauling through the traps at 6350 to 6667 rpm in 4th might be better off with, say, stock 2.73's and 26" tires and a World Class with an aftermarket 3.97/2.34/1.46/1.00/0.79 gearset hauling through the traps in 3 rd at 6667 rpm.

  19. #19
    Venomous Moderator Hissing Cobra's Avatar
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    Those are excellent numbers but I'm curious as to why there's no air/fuel graph on the dyno sheet. I'm thinking that with your compression, cam, heads, intake, and carb, you should be able to get a little bit more out of it. How much more? I have no idea. Also, I wouldn't normally say something like this but I have almost an identical combo with a slightly smaller cam than yours and it made 420 rwhp/380 rwt with all accessories intact (A/C pump, power steering, alternator). That's why I'm wondering what the air/fuel graph looks like.

    Mine is also a stock block (bored .30 over) and decked to create 10:8:1 compression. it's fitted with an Eagle cast crank and I-Beam rods, Anderson Motorsports N-91 cam (240/248@.050, .576/.576 with a 110 LCA), AFR 185's (58 cc's), Victor Jr., 1" aluminum spacer, and a Holley 650 double pumper. It's got a full MSD ignition (6AL, distributor, Blaster II coil), and a full Mac exhaust (1-3/4" longtubes, off-road H-pipe, and 2-1/2" catback system). It runs through a stock T-5 (I took my Tremec out because I hated it), and an 8.8 with 4.30 gears and a Detroit Locker unit. On the track, I leave at 4,500 rpms and it'll run mid to high 11's @ 117-121 on 26x11.5 ET Streets (3,300 lbs. with me in it). I wish I could leave the line at 6,000 rpms but I don't have the suspension for that type of aggressive launch, thus anything higher than 4,500 and it'll spin.

    I think you'll realize your goal of 400rwhp if you're able to see what the air/fuel curve is like and make some changes if need be. If not, you should be solidly into the 11's anyway. With a ton of weight reduction, you may even realize your goal of the high 10's - especially if you can leave the line at 6,000 rpms on that 28" tall tire that you'd like to run.
    Last edited by Hissing Cobra; 11-08-2017 at 03:31 PM.
    Pete

    1979 Mustang Cobra
    347/T-5/4.30's
    420 rwhp/380 rwt (New Motor)
    11.49 @ 121.86
    306/T-5/4.30's (Old Motor)
    307 rwhp/278 rwt
    12.38 @ 111.38


    1989 Mustang LX
    302/T-5/3.73's
    Daily Driver
    14.66 @ 95.63

  20. #20

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    Quote Originally Posted by Hissing Cobra View Post
    Those are excellent numbers but I'm curious as to why there's no air/fuel graph on the dyno sheet. I'm thinking that with your compression, cam, heads, intake, and carb, you should be able to get a little bit more out of it. How much more? I have no idea. Also, I wouldn't normally say something like this but I have almost an identical combo with a slightly smaller cam than yours and it made 420 rwhp/380 rwt with all accessories intact (A/C pump, power steering, alternator). That's why I'm wondering what the air/fuel graph looks like.

    Mine is also a stock block (bored .30 over) and decked to create 10:8:1 compression. it's fitted with an Eagle cast crank and I-Beam rods, Anderson Motorsports N-91 cam (240/248@.050, .576/.576 with a 110 LCA), AFR 185's (58 cc's), Victor Jr., 1" aluminum spacer, and a Holley 650 double pumper. It's got a full MSD ignition (6AL, distributor, Blaster II coil), and a full Mac exhaust (1-3/4" longtubes, off-road H-pipe, and 2-1/2" catback system). It runs through a stock T-5 (I took my Tremec out because I hated it), and an 8.8 with 4.30 gears and a Detroit Locker unit. On the track, I leave at 4,500 rpms and it'll run mid to high 11's @ 117-121 on 26x11.5 ET Streets (3,300 lbs. with me in it). I wish I could leave the line at 6,000 rpms but I don't have the suspension for that type of aggressive launch, thus anything higher than 4,500 and it'll spin.

    I think you'll realize your goal of 400rwhp if you're able to see what the air/fuel curve is like and make some changes if need be. If not, you should be solidly into the 11's anyway. With a ton of weight reduction, you may even realize your goal of the high 10's - especially if you can leave the line at 6,000 rpms on that 28" tall tire that you'd like to run.
    I ran almost an identical motor with 3:73 8.8 on Drag radials and and Edelbrock RPM heads ported and polished w/ a over-carbed 750 vac. Holley, leaving at 4000 and ran a best of 11.77......117mph .so its a 2 time proven formula in a 347.

  21. #21
    Venomous Moderator Hissing Cobra's Avatar
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    Quote Originally Posted by GT 350 View Post
    I ran almost an identical motor with 3:73 8.8 on Drag radials and and Edelbrock RPM heads ported and polished w/ a over-carbed 750 vac. Holley, leaving at 4000 and ran a best of 11.77......117mph .so its a 2 time proven formula in a 347.
    It sure is!
    Pete

    1979 Mustang Cobra
    347/T-5/4.30's
    420 rwhp/380 rwt (New Motor)
    11.49 @ 121.86
    306/T-5/4.30's (Old Motor)
    307 rwhp/278 rwt
    12.38 @ 111.38


    1989 Mustang LX
    302/T-5/3.73's
    Daily Driver
    14.66 @ 95.63

  22. #22

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    Quote Originally Posted by Hissing Cobra View Post
    Those are excellent numbers but I'm curious as to why there's no air/fuel graph on the dyno sheet. I'm thinking that with your compression, cam, heads, intake, and carb, you should be able to get a little bit more out of it. How much more? I have no idea. Also, I wouldn't normally say something like this but I have almost an identical combo with a slightly smaller cam than yours and it made 420 rwhp/380 rwt with all accessories intact (A/C pump, power steering, alternator). That's why I'm wondering what the air/fuel graph looks like.

    Mine is also a stock block (bored .30 over) and decked to create 10:8:1 compression. it's fitted with an Eagle cast crank and I-Beam rods, Anderson Motorsports N-91 cam (240/248@.050, .576/.576 with a 110 LCA), AFR 185's (58 cc's), Victor Jr., 1" aluminum spacer, and a Holley 650 double pumper. It's got a full MSD ignition (6AL, distributor, Blaster II coil), and a full Mac exhaust (1-3/4" longtubes, off-road H-pipe, and 2-1/2" catback system). It runs through a stock T-5 (I took my Tremec out because I hated it), and an 8.8 with 4.30 gears and a Detroit Locker unit. On the track, I leave at 4,500 rpms and it'll run mid to high 11's @ 117-121 on 26x11.5 ET Streets (3,300 lbs. with me in it). I wish I could leave the line at 6,000 rpms but I don't have the suspension for that type of aggressive launch, thus anything higher than 4,500 and it'll spin.

    I think you'll realize your goal of 400rwhp if you're able to see what the air/fuel curve is like and make some changes if need be. If not, you should be solidly into the 11's anyway. With a ton of weight reduction, you may even realize your goal of the high 10's - especially if you can leave the line at 6,000 rpms on that 28" tall tire that you'd like to run.
    Thanks.

    I didnt even think about an AFR graph, maybe when I get back I can find a dyno so I can check that out. From the tuner this is what he said about afr and timing,

    I tried different things on the dyno with timing and afr, your car ended up liking afr of about 12.5-12.7 and 38 deg total advance.

    In the distributor I left the stock advance that was in 21 deg so it has around 17-18 at idle currenly and then at full advance around 4k rpm.”


    ive got most of the rest of the build planned out as far as suspension goes but im just trying not to blow all my money on it while I’m over here in Korea, lol.

  23. #23

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    17-18 is a lot of base advance. A slightly more aggressive advance curve on the dizzy may allow a little less base advance and more total advance. What's "right" depends upon your A/F. I would be concerned about some low/midrange detonation where you are right now unless I had info to disprove its existence.

    I ran my 302 VM1 EFI motor with mild SD friendly cam and premium fuel right at the ragged edge of detonation for many years. 14.5 degrees of advance was tolerated, but not 15. It's said that high swirl heads like my E6's account for as much as two degrees less timing needed for max power without detonation. An AFR185 swirls a lot less than a head like an Edelbrock of similar valve size, but I know my A9P 89LX with E7 heads only tolerated 15.5 degrees of base advance and she HATED me for it. Both cars 3 core radiators were MANDATORY on the street any time it was warmer than 75 degrees outside. They were overheating pigs the moment the AC was turned on without one.

    the above were street cars primarily and the low/mid advance was dialed up as much as possible without detonation and the A/F was getting quite lean but that is where the fuel efficiency is and they both had forged pistons for a reason I reckon. They tolerated it. My 86 has nearly 1/2 million miles and original head gaskets so one might say it even thrived considering it's a low 13 second car on street tires.

    Anyway - I'd watch it a bit to make sure you don't chuck a head gasket or crack a block down there.

    Good luck reaching your goals!

  24. #24
    Venomous Moderator Hissing Cobra's Avatar
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    I agree that 17-18 is a lot of base advance. If you look at charts for MSD distributors, you can choose spring combos to get your total timing in by a certain RPM. On my old 306 dual quad motor, the timing was set at 16 degrees base timing and 34 degrees "all in" at 3,000 rpms. With my 347, it will only tolerate 14 degrees base timing and 32 "all in" by 3,000 rpms. I have one "fat" spring and one "skinny" spring in my MSD distributor.

    I will say that all motors are different and it's good that your tuner has tried different things.
    Last edited by Hissing Cobra; 11-10-2017 at 04:20 PM.
    Pete

    1979 Mustang Cobra
    347/T-5/4.30's
    420 rwhp/380 rwt (New Motor)
    11.49 @ 121.86
    306/T-5/4.30's (Old Motor)
    307 rwhp/278 rwt
    12.38 @ 111.38


    1989 Mustang LX
    302/T-5/3.73's
    Daily Driver
    14.66 @ 95.63

  25. #25

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    Matt and the guys at the shop are first class. I was wondering about the cam specs. Is that a custom cam or ?

    Sent from my SAMSUNG-SM-G890A using Tapatalk

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